[johndallman]

Pressure Points is the IQ/H esoteric martial-arts skill of striking pressure points to disable. There is a prerequisite of Trained By A Master or Weapon Master, and no default, except possibly Esoteric Medicine-4 in a cinematic campaign. No skills default to Pressure Points. To use it, make a successful attack at -2 (plus any Hit Location modifiers) with Karate or an applicable weapon skill and get at least 1 point of damage past any DR, or successfully apply a Judo lock at -2 (see Technical Grappling). Then roll a Quick Contest between Pressure Points and the target's HT. If you win, you disable the target in a way, and for a duration, that depends on which part of their body you attacked. By default, the skill is specialised as Pressure Points (Unarmed), but other possible specialisations include (Bow), for blunt arrows, (Shortsword) for a baton or (Staff). Presumably, sharp weapons don't allow the effect to work, although it's not clear why.

Pressure Secrets is the IQ/VH esoteric martial-arts skill of striking pressure points to kill. It has prerequisites of Trained By A Master and Pressure Points at 16 or higher. There is no default, and no skills default to it. To use it, make an unarmed attack at -2 (plus Hit Location modifiers), or successfully apply a Judo lock at -2, then make a Pressure Secrets roll. If you succeed, damage (or pain, shock, etc. effects from a lock) is doubled. An attack to the vitals is possible, in which case damage is tripled. The skill is noted as unrealistic and potentially unbalancing.

Both of these skills seem to have first appeared in Martial Arts for GURPS 3e. They both take Physiology modifiers, but no other modifiers are noted. As usual for Physiology-modifier skills, you normally buy them for your own species, but it's possible to learn them for use on another species, if you can get the training.

Martial Arts is the main source for additional information on these skills. It's possible to be Resistant to them, and to use Body Control to resist Pressure Points. You can buy off the -2 to hit with them as a Technique, and they're subject to the Rule of 16. They may get to use Realistic Injury rules when other attacks don't, and Pressure Secrets can make small improvised weapons deadly. Both appear as cinematic skills in many of Martial Arts' styles.

These skills mostly appear on templates for cinematic martial artists; templates that use Pressure Points with weapons are rare. DF11 has the "Hand of Death", with a prerequisite of Pressure Secrets at 16+, while Low-Tech has equipment to boost Pressure Points and allows a First Aid technique to be based on the skill. Technical Grappling has more on both skills, and notes that Pressure Points is somewhat realistic, at least for inflicting pain, while Pressure Secrets is thoroughly cinematic. Yrth Fighting Styles covers several ways to run the interaction of chi powers and magic. Power-Ups 1: Imbuements doesn't actually modify these skills, but uses them as exemplars, while Power-Ups 2, 3 and 6 have examples of perks, talents and wildcard skills for them. Powers allows Pressure Secrets to attack the target's chi powers, and Chinese Elemental Powers expands on this, while Thaumatology offers Pressure Secrets as a highly alternative core skill for magic.

I've never used these skills, never having played a dedicated Martial Arts campaign. How effective are they in practice? How have you modified them?